What should I do on my roof?

(I don't know how to play the fiddle...*:D*)

Seriously, I'm debating what sort of solar might be best on our roof. My GF and I live in a suburban house in MA, latitude 42.583, we have a roof with a 12/12 pitch and one side facing pretty much due south. As I understand it, this would be about a perfect angle for mounting panels flat on the roof, correct?

We have a lot of woods on the lot, but the trees south of the house are far enough away I don't think they are a problem. We do have some 70'+ red oaks to the east and west of the house that don't overhang the roof but do provide some shadows. I could take them out, but don't really want to as they are nice trees. There is also a tall chimney on the west end of the roof that casts a pretty good, but narrow shadow. I haven't measured exactly, but estimate there is about 4-500 square feet of South facing roof surface.

Current energy:
* We mostly heat w/ wood in an EPAII approved stove, about 4 cords / season, I get log-length and process it myself - cost ?
* Natural Gas for backup heat (HVAC) DHW, cooking and clothes dryer - 20-30 therms /mo - $1.73 / therm
* Electric for the rest, 800-2,000 kWH / month, the big hits being the central AC (high efficiency unit) and swimming pool pumps (in-ground ~16Kgal) - $0.154 kWh

We would like to do something that would either make a serious dent in our utility bills, or improve our comfort level, preferably both. We also would prefer something that is reasonably priced and has a fairly short payback time.

My take is that I basically have three options, and am trying to decide what the best approach would be to make use of our limited roof space. I can put up grid tied PV, or do solar water heating for DHW, House heat, and / or pool heat.


I've done some rough estimates using the online estimator from FindSolar.com (How good are they, assuming you gave them as good an input as possible?)

Solar PV - 5.6 - 8.4kW of peak power, going for 7kW, they want 700 sq feet, and estimate $53K in cost (after gov't subsidies) with an 11-18 year payback. This is more are than we have in roof, and the cost seems awfully high, with a long payback. It would probably make the biggest dent in our electric bills, but not do much for comfort, and it's a big investment. Aside from doing the install myself, there isn't much I can do to reduce the costs (and who knows what that would do to subsidies and / or permitting, etc.)

Solar Pool Heat - 291 sqft, installed cost about $5K. We don't currently heat the pool at all, so it is "refreshing" (that's spelled C-O-L-D!) for most of the season, which limits our use of it. Warming the pool would increase our comfort, but since we don't currently pay anything for heat, there is no real way to figure a payback. It also means that the roof would only be doing useful work during the approximately 6 months of pool season.
Could probably reduce that cost considerably by home-brew panels, and self install, no impact on subsidies since there are none.

Solar DHW - The FindSolar folks didn't offer a "whole house heat" option, but solar DHW was the smallest panel size - 32.3 sqft, and about $5K installed price, $2.5K after subsidies. Doing a bigger number of panels, (how many more?) we could probably put some form of radiant heat into the house as well, which would give us increased comfort and a dent in our gas bills and reduce the amount of wood we need to burn. In addition, since we wouldn't be needing as much heat in the summer, so we could use the pool as a "heat dump" and get pool heating (at perhaps lower efficiency) as a "freebie"... I could probably reduce costs considerably by doing a good bit of self install and home-brew panel construction as well, and have fewer permitting and code restrictions to deal with.

What would you do if it was your roof?

Gooserider